JPH02116607A - Method and device for removing impurity gas from inert gas and for guaranteeing that hydrogen content is at very low level - Google Patents

Abstract

PURPOSE: To efficiently obtain highly purified inert gases, which contain just extremely low level of hydrogen by introducing impure inert gases into a housing and successively bringing two kinds of specific gas sorbing materials into contact with these inert gases.

CONSTITUTION: The impure inert gases (e.g.; helium) are introduced into the housing 102 of a gas purifying apparatus 100 from an inlet 108. The gases are brought into contact with the first gas adsorbing material 114 consisting of a non-volatile type getter alloy selected from a Zr-V-Fe alloy and a Zr-Fe alloy, by which the gases are purified. The purified inert gases are then purified by bringing the gases into contact with the second gas adsorbing material 116, which is a non-volatile type getter alloy of a compsn. consisting of 5 to 30 wt.% Al and the balance Zr. The resultant highly purified inert gases, which contain just the extremely low level of the hydrogen are recovered through a purified gas outlet 110. The resulted inert gases are adequately used at the time of production of semiconductor devices, etc.

COPYRIGHT: (C)1990,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus and method for removing impurity gases from inert gases and at the same time ensuring extremely low levels of hydrogen, in particular two The present invention relates to such methods and apparatus in connection with the use of getter alloys.

The manufacturing process of Enmei Keita (noble gas or rare gas helium,
It is necessary to use an inert gas such as neon, argon, krypton, xenon, etc. or nitrogen in a highly purified state. A particular example of such use is in the manufacture of semiconductor devices. Prior to use, the impure inert gas must be purified or purified by removing the contained contaminant gases such as CO1CO, CH4, O□, and H2.

British Patent Application Publication No. 2.177.079 A and No. 2
, 177.080 A describes a method for purifying inert gases to remove these impurity gases.

However, the methods in these literatures still leave room for improvement in terms of high purity of impurity gases, and do not provide any information on the problem of maintaining extremely low levels of hydrogen.

Although quantitative evidence has not yet been obtained that the rate of defects found during the manufacturing of semiconductor devices is related to the partial pressure of hydrogen present during the manufacturing process, the lower the hydrogen partial pressure, the fewer defects are found. I believe it to be true.

The object of the invention is to develop an improved device for the removal of impurity gases from impure rare gases and inert gases such as nitrogen.

Another object of the invention is to develop an apparatus for the purification of inert gases which ensures that the purified inert gases contain very low levels of hydrogen.

Yet another object of the present invention is to develop a method that provides for the removal of impurity gases from impure inert gases while ensuring that the highly purified product gases contain only very low levels of hydrogen. It is.

The present inventors have solved the above problem by flowing an impure inert gas through a housing that accommodates a first gas sorption substance and a second gas sorption substance, in which case A, the first gas the sorption material is a non-evaporable getter alloy selected from the group consisting of (a) an alloy of Zr-V-Fe; and (b) an alloy of Zr-Fe;
B. It has been found that it is effective for the second gas sorption material to be a non-evaporable getter alloy having a composition of 5 to 30% by weight Al and the balance Zr.

These two different specific getter alloys have never been used for this purpose.

Referring to the drawings, particularly FIG. 1, there is shown a gas purification apparatus 100 for removing impurity gases from an inert gas. Inert gas here means noble or rare gases such as helium, neon, argon, krypton and xenon, as well as nitrogen. The gas purification device 100 includes a housing 102 in the form of a cylindrical (generally cylindrical) shell 104, preferably made of metal, such as stainless steel. The cylindrical shell 104 is provided with an end cap 106.106° attached thereto in a gas-tight manner. The end cap 106.106° is also preferably made of stainless steel. End cap 106 is fitted with an inert gas inlet 108 in the form of a hollow cylinder, also preferably made of stainless steel. The end cap 106 is provided with a purified gas outlet 110. The purified gas outlet 110 is also cylindrical and preferably made of stainless steel. Cylindrical outer skin body 104 and end cap 1
06.106'' constitutes the hollow space 112 that accommodates the first gas sorption substance 114 and the second gas sorption substance 116.

The first gas sorption material 114 is preferably (a) Zr
(b) an alloy of Zr-Fe;

Here, the term "alloy" also includes intermetallic alloys.

The first gas sorption material 114 is comprised of a powder having an average particle size of less than about 125 μm and is in the form of a number of pellets formed by compacting and/or thermally sintering the powder. These pellets of first gas sorption material 114 are located in the first zone 11 adjacent to the inert gas inlet 108.
It is located within 8.

When the gas to be purified is a rare or noble gas such as argon, the first gas sorption material 114 is
It should be r-V-Fe alloy. In this case, the first gas sorption substance has the following weight percentages of the three elements as shown in the ternary composition diagram: (a) 75% Zr - 20% V - 5% Fe (b) 45%
Zr -20%v-35%Fe(c)45%Zr-5
Non-evaporable Zr-V- with a weight composition that lies within a triangle having a point defined by 0% V-5% Fe as a corner
It is a Fe getter alloy.

If the inert gas to be purified is nitrogen, the first
The gas sorption material 114 is a non-evaporable getter alloy of Zr-Fe and preferably consists of 15-30% by weight Fe-balance Zr.

The second gas sorption material 116 is a non-evaporable getter alloy having a composition of 5 to 30% by weight Al and balance Zr. A preferred example is 16% Al-balance Zr.

The second gas sorption material 116 is in the form of a compressed powder pellet, where the powder is less than 125 μm.

These pellets are located within the housing in a second zone 120 adjacent to the purified inert gas outlet 110.

The method of the present invention for removing impurity gases from an impure inert gas and ensuring that the purified product gas contains only extremely low levels of hydrogen includes passing the impure inert gas through an inlet into a housing. step and impure inert gas to (a) a non-evaporable getter alloy of Zr-V-Fe, and (
b) contacting a first gas sorption material selected from the group consisting of a non-evaporable getter alloy of Zr-Fe to produce a purified inert gas; Flowing through and contacting the second gas sorption material produces a highly purified inert gas containing extremely low levels of hydrogen. The second gas sorption material 116 is a non-evaporable getter alloy having a composition of 5 to 30% by weight Al and balance Zr. The highly purified inert gas containing very low levels of hydrogen exits through the purified inert gas outlet. The first gas sorption substance and the second gas sorption substance are maintained at a temperature of, for example, 350 to 450°C.

Reference examples and examples are shown below.

Beard 1 (Reference Example) A stainless steel housing of 7 CIT+ length and 1 cm diameter, equipped with inert gas inlet and outlet, was filled with compressed pellets of ZrzFe powder with particle size smaller than 125 μm. The pellet was cylindrical with a diameter of 4 mm and a height of 3 mm. The total weight of the pellets used was 14 g.

The apparatus was heated to 330°C and impure nitrogen was flowed through the apparatus.

The nitrogen impurity levels were as follows: impurity level pp
m” Yu H-HL Peek-tan LA 10 10 9
9B 9 8.5
7.5 9.5C998,58,5 A, B and C are optional designations for several cylinders of impure N gas used in this example.

After flowing impure N2 gas through the device for a total of about 350 hours, samples of ZrxFe were taken at various locations along the length of the device and analyzed for C10□, N, and N2 content.

FIG. 2 shows the results of the C content measurements, plotting the C content in am'' mbar mg-' on the y-axis as a function of position 1 cm of the sample from the inert gas inlet 108. .

FIG. 3 is a similar curve for H.

FIG. 4 is the expected profile of hydrogen partial pressure within the device.

This example shows that sorption of impurities occurs in a gradual manner throughout the device.

Medical Unit (Reference Example) A device similar to FIG. 1 was filled with 720 g of compressed pellets of 70% Zr-24,6% V-5,4% Fe powder with particle size less than 125 μm. The pellets were cylindrical with a diameter of 6 mm and a height of 4 mm.

Argon gas of nominal purity of 5 N (99,999%) was heated at several constant temperatures, an inlet pressure of 1.3 bar and 1 bar.
It was flowed through the apparatus maintained at an outlet pressure of r (1 atm). The Ar gas flow rate was 1β/min. After about an hour, 6
The two partial pressures were measured and plotted on the graph of FIG. The temperature was changed and the test repeated.

Curve A in FIG. 5 connects the points plotted at temperatures of 300°C, 350°C, 400°C, and 450°C.

Ushiyu (Example) Example 2 was repeated with the following exceptions. zr-V- similar to that used in Example 2 in the housing part adjacent to the gas inlet.
650 g of Fe pellets were charged. The remaining space adjacent to the gas outlet contains 84% Zr − with grain size less than 125 μm.
70 g of pellets of equal size made by intimately mixing and compressing 95% by weight of 16% Al alloy and 5% by weight of Al powder
filled with. Similar tests as for Example 2 were repeated at 400°C and 450°C. During each of these tests, Zr-V-F
The e alloy and the Zr-A1 alloy were at the same temperature. The results are shown as curve B in FIG.

As is clear from FIG. 5, the level of produced hydrogen impurities in the outlet gas was reduced by two orders of magnitude, ie, on the order of 1 part per 100.

Dish A (Example) Examples 2 and 3 were repeated, except that the Zr-V-Fe pellets were replaced by pellets of ZrJe and the gas to be purified was nitrogen. The outlet partial pressure of H3 was significantly reduced when Zr-Al pellets were present next to the gas outlet.

By developing an inert gas purification technology that guarantees that it contains only an extremely low level of hydrogen, the present invention aims to improve the quality of inert gases that require high-purity inert gases, such as in the manufacture of semiconductor devices. Contribute to the manufacturing of products.

Although one preferred embodiment of this invention has been described above, it is to be understood that many changes may be made within the scope of this invention.

Figure 1 is a partial sectional view of the apparatus of the invention for removing impurity gases from inert gases, ensuring that the highly purified gases contain only extremely low levels of hydrogen. be.

Figure 2 shows the impurity C as distributed throughout the apparatus after purifying the inert gas for a period of time in the apparatus of Figure 1.
It is a graph showing the concentration of O.

FIG. 3 is a graph similar to FIG. 2 showing hydrogen concentration.

FIG. 4 shows the partial pressure of hydrogen throughout the apparatus of FIG.

FIG. 5 shows the relationship between the prior art purification device and the present invention purification device.
It is a graph showing H2 partial pressure in highly purified inert gas.

100: 102: 104: 106. 108: l 10: 112: 114: 1 l 6: Gas purification (high purity) housing integumentary body 106’: End cover Inert gas inlet Purified gas outlet hollow space First gas sorption substance Second gas sorption substance Device

Claims (1)

[Scope of Claims] 1) An impure inert gas comprising a housing containing a first gas sorption substance and a second gas sorption substance, and an impure inert gas inlet and a purified inert gas outlet communicating with the housing. In an apparatus for removing impurity gases from a gas, A. the first gas sorption material is selected from the group consisting of (a) a non-evaporable getter alloy of Zr-V-Fe; and (b) Zr-Fe. B. An apparatus for removing impurity gas from an inert gas, wherein the second gas adsorption substance is a non-evaporable getter alloy having a composition of 5 to 30% by weight Al-balance Zr. 2) the impure inert gas is argon and A, the first
When the weight percent of the three elements of the gas sorption substance is shown in the ternary composition diagram, (a) 75% Zr-20%V-5%Fe (b) 45%Zr-20%V-35%Fe ( c) a non-evaporable Zr-V-Fe getter alloy with a weight composition such that it lies within a triangle with corners defined by 45% Zr-50% V-5% Fe; The gas sorption material is 16% by weight Al-balance Zr.
2. The device according to claim 1, wherein the getter alloy is a non-evaporable getter alloy having a composition of: 3) The impure inert gas is nitrogen and A, the first gas sorption substance is 15 to 30 wt% Fe-Z
B is a non-evaporable getter alloy consisting of B, a second gas sorption material comprising 16% Al by weight and the balance Zr.
2. The device according to claim 1, wherein the getter alloy is a non-evaporable getter alloy having a composition of: 4) A. The first gas sorption material is in the form of a plurality of compressed pellets of powder having an average particle size of less than 125 μm, and the pellets are located in a zone adjacent to the inert gas inlet within the housing. and B, the second gas sorption material is in the form of a compressed pellet of powder having an average particle size of less than 125 μm, and the pellet is located in a zone adjacent the inert gas outlet within the housing. 2. A device according to claim 1, characterized in that it is arranged in a. 5) passing the impure inert gas through the inlet into the housing in a manner that removes the impurity gas from the impure inert gas and ensures that the purified product gas contains only very low levels of hydrogen; B. contacting the impure inert gas with a first gas sorption material selected from the group consisting of (a) a non-evaporable getter alloy of Zr-V-Fe; and (b) Zr-Fe. C. flowing the purified inert gas through a second gas sorption material, which is a non-evaporable getter alloy having a composition of 5 to 30 wt% Al-balance Zr; and (D) recovering the purified inert gas containing extremely low levels of hydrogen through an inert gas outlet. An inert gas purification method comprising: 6) The impure inert gas is argon and the first gas sorption material is (a) 75% Zr-20%V-5%Fe ( b) 45%Zr-20%V-35%Fe (c) 45%Zr-50%V-5%Fe Non-evaporable Zr with a weight composition within a triangle having the corner angles defined by -V-Fe getter alloy. 7) The method of claim 5, wherein the impure inert gas is nitrogen and the first gas sorption material is a non-evaporable getter alloy consisting of 15-30% by weight Fe-Zr. 8) The second gas sorption material is 16% by weight Al-balance Zr.
6. The method according to claim 5, wherein the getter alloy is a non-evaporable getter alloy having a composition of: 9) the first gas sorption material is in the form of a number of compressed pellets of powder having an average particle size of less than 125 μm, and the pellets are arranged in the housing in a zone adjacent to the inert gas inlet; and maintained at a temperature of 350-450°C, and the second gas sorption material is 125μ
in the form of a plurality of pellets formed by compacting a powder having an average particle size of less than 7. A method according to claim 6, wherein the temperature is maintained at the same temperature as above.